A waste pyrolysis apparatus is known for the pyrolysis of waste, particularly of a scrap, residue-laden or industrial charge of pyrolyzable waste, with an indirectly heated pyrolysis reactor from which a pyrolysis gas pipe is fed to a combustion chamber. A process for disposing of waste is known which comprises pyrolyzing the waste and subsequently burning the pyrolysis gas produced.
It is possible to do away with certain problem waste materials in an environmentally friendly way with the help of pyrolysis.
By pyrolysis, I mean heating to effect chemical changes including gas production by the heating process alone.
By "waste or waste materials", I means particularly the so-called aged or ripened loads of waste such as earth contaminated with oil or solvents, animal residues, acid sludge and the like. Also, I include special waste such as old tires or residue from plastic insulated electrical cables. A solid material occurs as a product of this process which contains recoverable and/or landfill depositable substances. Furthermore a combustible pyrolysis gas is produced.
This pyrolysis apparatus is described in Austrian Patent No. 346 997. That the use of the pyrolysis product gas in the typical gas burner or in an internal combustion engine is associated with practical problems because of the composition of the pyrolysis gas and the different additives contained in it, is not disclosed by this reference.
Considerable expense is required to treat this pyrolysis gas in a peripheral unit as can be learned from German Patent documents Nos. 27 32 418, 24 32 504 and from U.S. Pat. No. 4,206,186.
Of course the formation of certain gaseous impurities such as halogen containing acids or sulfur dioxide can be avoided by introducing a fine grained basic material before or during the sulfurization process as has been disclosed is European Patent Application No. 0 111 081 and the above mentioned Austrian Patent No. 346 997. Then the expense for subsequent removal of these gas components is saved. On the other hand, a greatly increased dust content of the pyrolyzed gases causes an increased expense for dust removal.
One problem is that suitable customers for the pryolysis gas produced in reduced quantities and with poor quality are not always present. Use of the pyrolysis plant itself presupposes a suitable gas-purification apparatus.
An economically self sufficient pyrolysis process, i.e. a process which permits purification and use of the pyrolysis gas, requires a large investment. Such an expenditure can not always be economically justified. This is especially true when the amount of the materials to be removed--e.g. more so with industrial and scrap charges--is limited so that the plant is only useful for a limited time.